Air handling equipment such as a centrifugal fan working in conjunction with a heat exchanger is often used to heat or cool the air within a building. When the equipment is mounted outside and on top of or alongside the building, an enclosure is typically used to shelter it from the outside environment.
In many installations, the fan draws all its inlet air from return air ducts within the building. It is often preferred, however, to have the fan not only draw return air from the building but to also draw in a portion of fresh air from outside the building. The outside air can contribute to the freshness of the air supplied to the building and, depending on the relative inside to outside air temperatures, can also improve the overall efficiency of providing the building's heating and cooling needs.
Currently, air handling enclosures without an open fresh air inlet connecting the fan inlet to outside air are modified by removing a panel that covers a fresh air opening through the enclosure. Uncovering the opening provides a fresh air inlet whose flow therethrough is controlled by installing add-on air handling devices such as hoods, mist elimination filters, and dampers. By not using the existing cover panel, however, additional single-purpose panels must be manufactured and supplied to adapt the enclosure to receive the add-on devices.
Manufacturing these additional single-purpose panels is an unnecessary expense. Therefore, it is an object of the invention to reduce the number of these panels by providing a dual-purpose, two-position cover panel for air handling enclosures.
Another object of the invention is to provide cost effective means of modifying an air handling enclosure to include an open fresh air inlet.
Another object is to provide a two-position cover panel that in one position covers a fresh air opening through the enclosure, and in another position uncovers the opening and engages an add-on air handling device.
Yet another object is to provide a two-position cover panel that when engaged to an add-on air handling device, the cover panel extends over the device to serve as its rain sheltering hood.
These and other objects will be apparent from the attached drawings and the description of the preferred embodiments that follow below.